This invention relates generally to machines such as rotary printing presses having rollers, cylinders or the like that need replacement, and pertains more specifically to means for use in replacing such rollers or the like. Still more specifically, the invention deals with how to replace an inking roller of a rotary printing press when it is worn or impaired, that roller being not only rotated but axially reciprocated during printing operation.
Japanese Examined Utility Model Publication No. 6-5891 is hereby cited as teaching a typical conventional method of inking roller replacement. It suggests the use of an inking roller having a pair of bosses projecting coaxially from its opposite ends. These bosses are received in holes in the opposed, enlarged ends of a pair of journals which are coaxially supported by bearing portions on confronting frame means of the press for both rotation and axial reciprocation with the roller. In order to make the roller removable from the journals for replacement, the enlarged ends of the journals are bisected, and the holes are each defined by a fixed segment of semicylindrical shape that is integral with one journal, and a removable segment of like shape that is screwed to the fixed segment to engage one roller boss therebetween. The journals are detachable from the roller bosses by unscrewing the removable segment. Removably mounted under the inking roller are a pair of medially pivoted rails along which the roller, disconnected from the journals, is to roll to a position of withdrawal from the machine.
For uncoupling this prior art inking roller from the journals, the roller must first be rotated with the journals to such an angular position that the mating surfaces of the fixed and removable segments of the enlarged journal ends are at an angle of approximately 62 degrees to the perpendicular. The journals are locked in this angular position by a pair of positioning arms held against them.
Then the pair of guide rails are turned about their medial pivots by manipulation of turnbuckles until the rails become engaged, each at one end thereof, in annular grooves which are cut in the bosses on both ends of the inking roller. The rails are now held at such an angle that their ends engaged with the inking roller are lower than the other ends. A pair of roller retainers are then mounted one to each guide rail for retaining the roller thereon against accidental rolling.
Then comes the step of unscrewing the removable segments of the enlarged journal ends from the fixed segments and thereby freeing the terminal bosses of the inking roller, although the bosses are now still cased in the half-holes in the fixed segments because of the above specified angular position of the journals. Then the turnbuckles are again manipulated to make the guide rails horizontal, whereupon the roller bosses will come out of the half-holes in the fixed segments onto the guide rails. Then, with the roller retainers removed, the inking roller is rolled over the guide rails to a preassigned unloading position.
The above summarized method of inking roller replacement is objectionable in more reasons than one. The first objection concerns the bisecting of the enlarged ends of the journals in defining holes for receiving the inking roller bosses. Such journals are difficult to manufacture, and it is even more difficult to connect and disconnect the roller bosses to and from the journals. The journals must be held with the mating surfaces of the fixed and removable segments more or less exactly at the noted angle of 62 degrees to the perpendicular for engaging and disengaging the roller bosses. No smooth engagement and disengagement is possible when the journals are in other than the required angular position.
Another objection arises from the fact that the inking roller rotates and axially reciprocates at the same time. As an inevitable result of this dual motion of the roller, the annular grooves of the roller may not be aligned with the guide rails when the roller is rotated to the required angular position for connection to or disconnection from the journals. Should the roller be then further rotated, and so moved axially, to bring the grooves into alignment with the guide rails, the roller would turn away from the required angular position. This difficulty is averted according to the prior art by making the guide rails movable back and forth axially of the roller, at the cost of additional means and additional labor.
A further objection to the prior art is the multiplicity and complexity of the parts and components needed for roller replacement. They include, in addition to the indispensable guide rails, the pair of turnbuckles for pivotally moving the guide rails, the pair of roller retainers for preventing the undesired rolling of the roller on the guide rails, and the pair of positioning arms for angularly positioning the journals with respect to the roller. All these parts must be mounted to the frames of the printing press each time the inking roller is replaced, and dismounted upon completion of replacement, making the roller replacement very troublesome and time-consuming. Furthermore, the prior art replacement means were costly in construction and susceptible to malfunctioning.